Enamelin is a major extracellular component of dental enamel, yet its role in the formation of this tissue has not been extensively explored. Specific aims of this project are: 1) to determine the temporal and spatial expression of enamelin during the secretory, transition, and maturation stages of enamel biomineralization; 2) to generate a enamelin knockout mouse and characterized enamel formation in the absence of enamelin expression; and 3) to investigate the regulation of mouse enamelin gene expression. Planned approaches to accomplish these aims are to examine the temporal and spacial distribution of enamelin gene expression using immunohistochemistry and in situ hybridization, to knock out the enamelin gene and examine ensuing changes in enamel formation, and to utilize systematic deletion/mutation analysis to identify regions of the enamelin gene necessary for cell and stage-specific expression in ameloblasts. Information gained from these studies taken together with findings related to the transcriptional regulation of other proteins such as amelogenin, ameloblastin, EMSP1 and DSPP will allow a comprehensive understanding of the regulation of structural gene expression during amelogenesis.